Multi-stage concentration of coffee

ABSTRACT

In a staged freeze concentration process for concentrating coffee solution, ice crystals are removed from the system after the first stage from less concentrated coffee solution. Ice crystals removed from the more concentrated coffee solution in the second stage are added to incoming feed. Coffee solution from which ice crystals are separated in the second stage is removed from the system as a product.

I Umted States Patent 1 1 1 3,762,177 Ganiaris 1 1 Oct. 2, 1973 [541 MULTI-STAGE CONCENTRATION OF 2,800,001 7/1957 Wenzelberger 62/124 COFFEE 3,501,924 13/1970 Ashley 3,102,036 8/1963 Smith 99/31 X {76] Inventor: Neophytos Ganiaris, 3671 Husdon 3,128,188 4/1964 Mclntire 62/123 x Manor Ter., Riverdale, N.Y. 10463 Filed Ma 12 1971 FOREIGN PATENTS OR APPLICATIONS y 863,348 3/1961 Great Britain 62/58 [21] App1.No.: 142,666

Related US. A lication Data Primary Examiner-Wi1liam E. Wa ner PP y [60] Division ofSer. N0. 652,532, July 11, 1967, Pat. N0. Alwmeywllllam Dwcker 3,620,034, which is a continuation-in-part of Ser. No. 572,365, Dec. 8, 1965, abandoned, which is a continuation-in-part of Ser. No. 321,020, Nov. 4, 1 1 RA 1963, Pat. No. 3,283,522.

In a staged freeze concentration process for concen- [52] U S Cl 62/123 99/152 trating coffee solution, ice crystals are removed from [51] 6 9/04 the system after the first stage fromiess concentrated [58] Fie'ld 123 coffee solution. Ice crystals removed from the more concentrated coffee solution in the second stage are added to incoming feed. Coffee solution from which ice [56] Reerences Cited crystals are separated in the second stage is removed UNITED STATES PATENTS from the system as a product. 2,389,732 11/1945 Ke11ogg 62/58 X 1 Claim, 1 Drawing Figure PATENTEWZW 3,762,177 V MULTI-STAGE CONCENTRATION OF COFFEE This application is a division of Ser. No. 652,532 filed July 11, 1967, now U.S. Pat. No. 3,620,034, which is a continuation-in-part of Ser. No. 512,365 filed Dec. 8, 1965, and forfeited on June 20, 1969, which in turn is a continuation-in-part of Ser. No. 321,020 filed Nov. 4, 1963 and now US. Pat. No. 3,283,522 of Nov. 8, 1966.

BACKGROUND OF THE INVENTION In the freeze concentration of coffee, a coffee solution is passed through a series of crystallizers to provide a slurry of ice crystals in a concentrated coffee solution. The ice crystals are separated from the concentrated coffee solution in a centrifuge and washed. Even when crystals of a uniform and optimum size are produced, considerable valuable coffee solids may be lost with ice crystals from which it is difficult to remove the more concentrated coffee solution.

SUMMARY OF THE INVENTION This invention provides for the centrifuging of ice crystals from a multi-stage freeze concentration system for coffee which provides coffee solution at a concentration of over 37 percent from a feed at a concentration of about 26 percent by centrifuging and removing the ice crystals from the system in a first centrifuge which separates crystals from a coffee solution at a concentration of less than 30 percent leaving an early or first stage crystallizer. The solution from the first centrifuge is passed through an additional crystallizer and a second centrifuge from which a product stream of a coffee solution of over 37 percent is withdrawn, ice from the second centrifuge being recycled by being added to the feed.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE of the DRAWING is a schematic diagram of a 26 for the freeze concentration of coffee according to this invention. that Referring to the DRAWING in detail, a feed solution of 36 percent by weight coffee dissolved solids enters feed tank through pipe 11. Pump 12 draws this solution from feed tank 10 and passes it through pipe 13 to enter crystallizer 14. The solution passing through pipe 13 from tank 10 will be from 13 percent to 24 percent coffee dissolved solids. This lower coffee content results from the fact tht the solution is diluted because ice enters tank 10 from centrifuge 15 through pipe 16 and because wash water from centrifuge 17 passes into tank 10 through pipe 18. Thus wash water and the melted ice dilute the feed solution entering crystallizer 14.

A pump 19 may partially recirculate through pipe 20 the slurry of ice crystals and coffee solution leaving crystallizer 14 until the coffee solution contains 26 to 30 percent coffee dissolved solids. This slurry then passes through pipe 21 to enter centrifuge 17. Mother liquor is separated from the ice crystals in centrifuge 17 and passes through pipe 22 to the mother liquor tank 23. Wash water enters centrifuge 17 through pipe 24 to wash ice crystals therein and flow to tank 10 through pipe 18. Ice passes from centrifuge 17 through pipe 25 to enter the ice tank 26. Some ice melts in tank 26 to be recirculated by pump 27 through pipe 24 as wash water. Ice passes from the system through pipe 28.

The 26 to 30 percent coffee dissolved solids solution in mother liquor tank 23 is pumped by pump 30 through pipe 31 to the second stage crystallizer 32. A slurry of ice crystals in at least a 37 percent coffee solution leaves crystallizer 32 through pipe 33 to enter centrifuge 15. The 37 percent coffee dissolved solids solution leaves centrifuge 15 through pipe 34 as a product. By means of pipe 36 and valve 36, this solution may be recirculated through crystallizer 32.

By means of valve 37 and pipe 38 mother liquor may be recirculated through crystallizer 14. This recirculation is required to raise the concentration of the solution in pipe 13 entering crystallizer 14 above the concentration of the feed while keeping it below 30% coffee dissolved solids. Excessive recirculation through pipe 20 could also serve to concentrate the feed from pipe 13, but this would result in too high a percentage of ice crystals in the crystallizer 32 which would reduce the rate of crystal growth. Recirculation through pipes 20 and 38 should be balanced and controlled so that the percentage of ice crystals by weight in solution in crystallizer 14 is between 20 and 30 percent. If the percentage of ice crystals is too low, below 15 percent by weight, as when pipe 20 is not used for recirculation, excessive nucleation and small and non-uniform crystals result which are difficult to centrifuge. When centrifuging ice crystals from the system from a 26 to 30 percent solution as described, less than 1 percent coffee solids by weight will be lost with the ice.

While this invention has been shown and described in the best form known, it will nevertheless be understood that this is purely exemplary and that modifications may be made without departing from the spirit and scope of the invention except as' it may be more limited in the appended claims wherein:

What is claimed is:

1. A system of apparatus for preparation of a concentrate of coffee from an aqueous coffee extract, comprisng:

a. serially connected crystallizer means for partially freezing and recirculating through a crystallizer means the aqueous coffee extract having 13 to 24 percent dissolved solids to form a mixture of ice and a more concentrated extract,

b. centrifuge means for separating said ice from said mixture whereby a portion of said concentrated extract adheres to the ice,

c. means for conducting the mixture from the crystallizer means (a) to the centrifuge means (b),

d. means washing the ice with liquids and coacting with the centrifuge means (b) to reduce the amount of concentrated extract adhering to the lcfi. 

1. A system of apparatus for preparation of a concentrate of coffee from an aqueous coffee extract, comprisng: a. serially connected crystallizer means for partially freezing and recirculating through a crystallizer means the aqueous coffee extract having 13 to 24 percent dissolved solids to form a mixture of ice and a more concentrated extract, b. centrifuge means for separating said ice from said mixture whereby a portion of said concentrated extract adheres to the ice, c. means for conducting the mixture from the crystallizer means (a) to the centrifuge means (b), d. means washing the ice with liquids and coacting with the centrifuge means (b) to reduce the amount of concentrated extract adhering to the ice. 